1. Field of the Invention
The present invention relates generally to inscription of images on a surface and particularly, but not by way of limitation, to laser-inscripted bar codes on a glass microscope slide.
2. Description of Related Art
Permanent identification of microscope slides has long been a difficult task. The glass of such slides must be as transparent as possible to facilitate viewing of test samples on the slides under a microscope. As a consequence, marking the slides with hand-written information correlating the test samples with the proper patient presents a challenge.
Further, microscope slides are typically exposed to a wide variety of laboratory solvents, reagents, stains and chemicals, which may remove, blur or obscure critical information on the slides. Consequently, it is important that any marking system for microscope slides be resistant to being dissolved, blurred or obscured by substances used in laboratories.
At the very least, misidentifying a slide destroys professional and public confidence in laboratory test results. Erroneously correlating an abnormal slide with a normal patient may subject a patient and the patient's family to needless anxiety and perhaps unnecessary medical treatment. Conversely, incorrectly identifying a normal slide with an abnormal patient may cause a condition to go untreated and result in debilitation, an excessively long recovery period or even death for the patient.
The possibility of such harsh consequences from misidentifying microscope slides makes an extremely reliable marking system for microscope slides a critical requirement. Thus, a number of devices have been designed over the years for permanently labelling microscope slides.
For example, U.S. Pat. No. 4,481,246, issued to Melisz et al., discloses a microscope slide having a raised marking surface formed of a pigmented resinous material such as epoxy resin, which is absorptive and retentive of marking ink. The epoxy resin accepts the marking of felt-tip pens, india ink, ballpoint pen ink and pencil.
U.S. Pat. No. 4,679,914, issued to Rosenberg, discloses a microscope slide with top and bottom marking surfaces.
A raised marking surface formed of pigmented resinous material, such as an epoxy resin, is disposed on one side of the slide and a frosted marking surface is located on the other side of the slide. The frosted marking surface is produced by sand-blasting, acid etching or mechanical abrading.
U.S. Pat. No. 5,111,344, issued to Robinson, Jr., discloses a ceramic-coated microscope slide. This particular slide is made of low annealing temperature glass and has an opaque, porous, ceramic marking surface permanently fused to the glass.
Each of these slides provides a marking surface for identifying information written with pen or pencil. However, none of these slides provides permanent machine-readable indicia for identification of the slide and for verification with hand-written information.